Wholly aromatic polyamide

ABSTRACT

Aromatic copolyamides, soluble in organic polyamide solvents, comprise at least 95 mol % of the recurrent structural units of the formulae   OCArCO A  HNAr&#39;NH B  &lt;IMAGE&gt; C  &lt;IMAGE&gt; D  and up to 5 mol % of structural units containing m-bonds. -Ar- and -Ar&#39;- are here divalent, unsubstituted or substituted aromatic radicals, the valency bonds of which are in the para-position or in a comparable coaxial or parallel position, and -R and -R&#39; are different from one another and are lower alkyl radicals or lower alkoxy radicals.

DESCRIPTION

The invention relates to novel, wholly aromatic polyamides of thedicarboxylic acid/diamine type, which can be spun from their solutionsin organic solvents, and to shaped structures produced from the, such asfilaments, fibers, fiber pulp, films, sheets and membranes of very highinitial modulus (modulus of elasticity), and also to processes forpreparing them.

As is known, aromatic polyamides (polyaramides) are raw materials ofhigh thermal and chemical stability and low inflammability. Thus, forexample, fibers and films of such raw materials show very goodmechanical properties, such as a high strength and high initial modulus(modulus of elasticity), and are very suitable for fields of applicationin industry--for example for reinforcing plastics or as filtermaterials.

The preparation of the polymers required for this purpose is bestcarried out in a known manner by reacting aromatic diamines witharomatic dicarboxylic acid dichlorides in aprotic organic solvents ofthe amide type (N,N-dimethylacetamide, N-methylpyrrolidone, N,N,N',N'-tetramethylurea and the like)--if necessary in the presence ofcalcium halides or lithium halides--and neutralizing the hydrogenchloride formed, for example with calcium oxides.

Polyaramides of high strength and high initial modulus are those inwhich the amide bonds on the aromatic nuclei are mutually orientedcoaxially or almost parallel, whereby rigid, rod-like polymer moleculesare formed.

An example of a typical polyamide of this type ispoly(p-phenyleneterephthalamide). Filaments of this material have beendescribed, for example, in German Pat. No. 2,219,703.

This polyamide has a number of advantages, but its preparation and itsprocessing are very difficult. Because of the poor solubility in polarorganic solvents --and in particular also in the presence of inorganicsalts such as calcium chloride or lithium chloride as solubilizers--thispolymer already precipitates from the reaction medium shortly after ithas been formed. It must be isolated, washed, dried and then redissolvedin a spinning solvent. The preferred solvent for preparing the spinningsolutions is concentrated sulfuric acid, which causes special problemsin handling (occupational safety, corrosion) and waste disposal.

Attempts have therefore been made to avoid these difficulties bydeveloping copolyamides which have good solubility in the known amidesolvents and which can also be readily spun and the filaments of whichare distinguished, after drawing, by high strength values and initialmoduli.

Thus, for example in DE-A-2,144,126, the preparation of soluble aromaticpolyamides of high modulus of elasticity was described, according towhich substituted 3-(p-aminophenoxy)-4-aminobenzanilides give, withterephthaloyl chloride, readily soluble polyamides which can be spun anddrawn to give filaments of good strengths and initial moduli.

The increased solubility is here caused by the metaorientation and theoxygen bridge atom.

In German Pat. No. 2,556,883 and in German Offenlegungschrift No.3,007,063, copolyamides of terephthalic acid, p-phenylenediamine and3,4'-diaminodiphenyl ether are described which, in amide solvents, giveisotropic solutions which can readily be spun. The filaments areprovided with high strengths and moduli by very extensive drawing. Adisadvantage in the two abovementioned processes is that the requiredunsymmetrical diamines can be prepared and purified only by veryinvolved processes.

For this reason, terephthalamides with 3 diamine components in certaindefined fractions are described in German Offenlegungsschriften Nos.3,510,655 and 3,605,394 or in European patent aplication No. 0,199,090,respectively, which are readily soluble in amide solvents and, bydeformation, give filaments or films of very good strengths and moduli.

Because of the content of non-aromatic chain constituents, as --O-- or--CH₂ -- groups, the moduli described in the last mentionedpublications--up to 68 N/tex is mentioned in German OffenlegungsschriftNo. 3,510,655, and up to 79 N/tex in German Offenlegungsschrift No.3,605,394--are not yet sufficiently high for certain intendedapplications.

Filaments of the abovementioned poly-(p-phenyleneterephthalamide)described in German Pat. No. 2,219,703 reach moduli of up to 99 N texonly after an expensive thermal aftertreatment (cf. also U.S. Pat. No.3,767,756, column 11, and German Pat. No. 2,219,703, page 14).

The present invention is therefore based on the object of providingaromatic copolyamides of a type which can be converted with the use ofamide solvents into shaped structures which are then distinguished by anumber of physical properties. In the production of filaments andfibers, in particular high strengths and very high initial moduli shouldbe achievable after appropriate drawing steps. The monomers required forpreparing the copolyamides should be readily accessible, and the polymersolutions obtained by the polycondensation should be capable of spinningor shaping directly after a filtration process and appropriatedegassing.

Novel aromatic copolyamides have not bee found which are composedpredominantly of para-substituted aromatic chain constituents and,surprisingly, are nevertheless soluble in amide solvents and can beprocessed from these solutions to give shaped structures such asfilaments, fibers, fiber pulp and films or sheets. These copolyamidescomprise at least 95 mol %, preferably 100 mol %, of the followingrecurrent--exclusively rigid--structural units ##STR2## and up to 5 mol% of structural units E and/or F which contain m-bonds and are derivedfrom aromatic dicarboxylic acids (E') and/or from aromatic diamines(F'), the total of the mol fractions of the structural units A+E and thetotal of the mol fractions of the structural units B+C+D+F beingsubstantially the same.

In these formulae

--Ar-- and --Ar'-- are divalent aromatic radicals, the valency bonds ofwhich are in the para-position or in a comparable coaxial or parallelposition and which may be substituted by one or two inert radicals suchas lower alkyl or halogen, and

--R and --R' are different from one another and are lower alkyl radicalsor lower alkoxy radicals.

The valency bonds which are in a coaxial or parallel position, point inopposite directions. An example of coaxial bonds pointing in oppositedirections are the naphthylene 1,4-bonds. Examples of parallel bondspointing in opposite directions are, for example, naphthalene 1,5- or2,6-bonds, whereas the naphthalene 1,8-bonds point in the same directionin parallel.

Divalent aromatic radicals representing --Ar--, in which the valencybonds are in the para-position or in a comparable coaxial or parallelposition, are mononuclear or dinuclear fused aromatic radicals such as,for example, 1,4-phenylene, 1,4-naphthylene, 1,5-naphthylene,2,6-naphthylene.

Divalent aromatic radicals representing --Ar'--, in which the valencybonds are in the para-position or a comparable coaxial or parallelposition, are mononuclear or dinuclear fused aromatic radicals such as,for example, 1,4-phenylene, 1,4-naphthylene, 1,5-naphthylene and2,6-naphthylene. 1,4-Phenylene is preferred for --Ar-- and --Ar'--.

The radicals --Ar-- and --Ar'-- can be monosubstituted or disubstitutedby lower alkyl radicals, i.e. straightchain or branched alkyl radicalshaving 1 to 4 carbon atoms, or by halogen, in particular by F, Cl or Br.Preferred alkyl substituents are straight-chain and are, in particular,methyl and ethyl. The preferred halogen substituent is chlorine.

The polyamides according to the invention can contain the unsubstitutedradicals --Ar-- and --Ar'-- and the alkyl- and/or halogen-substitutedradicals --Ar-- and --Ar'-- side by side in varying proportions.

The polyamide can here contain one type or several types of substitutedradicals --Ar-- and --Ar'--; for example, it can contain exclusivelymethyl-substituted --Ar-- and/or --Ar'-- radicals, or it can containproportions of --Ar-- and/or --Ar'-- radicals with different alkylsubstituents and/or with halogen substituents.

However, the polyamides according to the invention can also containunsubstituted or substituted radicals --Ar-- and --Ar'-- exclusively.For cost reasons, those polyamides according to the invention arepreferred which contain only unsubstituted radicals --Ar-- or --Ar'-- orsuch radicals substituted up to the extent of about 30 mol %.

Lower alkyl radicals and lower alkoxy radicals, which can be representedby --R and R', are likewise straight-chain or branched and have 1-4carbon atoms. Preferably, R and R' are straight-chain radicals andespecially radicals having 1-2 carbon atoms. Particularly preferably, Rand R' are methyl and methoxy.

The radicals R and R' are different from one another. This means that Rand R' can, for example, be two different alkyl radicals or twodifferent alkoxy radicals. Preferably, however, the radicals R are alkylradicals and the radicals R' are alkoxy radicals. In particular, R ismethyl and R' is methoxy.

The structural units B, C and D originating from the diaminesco-condensed into the polyamide are contained in the aromatic polyamidesaccording to the invention only in the following defined mol percentageranges, relative to the total quantity of components B, C and D:

    ______________________________________                                        Structural unit B: 20-30 mol %, preferably 25-30 mol %,                       Structural unit C: 35-55 mol %, preferably 40-50 mol %,                       Structural unit D: 15-40 mol %, preferably 25-30 mol %.                       ______________________________________                                    

These mol % data here relate to the total quantity of the diaminestructural units B, C and D.

In addition to the structural units with bonds in the para-position orcomparable bonds pointing in opposite directions coaxially or inparallel, the polyamides according to the invention can have up to 5 mol%, relative to all the structural units, of structural units E and Fcontaining m-bonds.

Within the meaning of the present invention, structural units E and Fcontaining m-bonds are those which contain an aromatic nucleus, of whichthe bonds lying in the chain of the polymer molecule are in them-position relative to one another.

Examples of such structural units are the radicals of isophthalic acid,m-phenylenediamine, 3,4'-diaminodiphenyl or alkyl- and/oralkoxy-substitution products thereof, or 3,4'- or3',4-diaminobenzanilide.

It is self-understood to a person skilled in the art that the total ofall the structural units (A+E) derived from aromatic acids and the totalof all structural units (B+C+D+F) derived from aromatic amines aresubstantially equal, i.e. that they differ by about 1% as a maximum,preferably by 0.2% as a maximum, and especially that they are equalwithin the range of the measurements and metering which are possible inpractice.

The aromatic polyamides according to the invention are soluble in polarorganic aprotic solvents and can be processed directly from thesesolutions to give shaped structures.

The structures thus obtained are distinguished by a combination of verygood technological properties.

In conjunction with the solubility in organic solvents and the economicand ecological advantages resulting therefrom, this processabilityrepresents an extremely valuable enrichment of technology in the fieldof wholly aromatic polyamides.

The outstanding technological properties of the shaped structuresaccording to the invention are based on the incorporation of the aminecomponents B, C and D within the limits indicated above. As can be seenfrom the comparative experiments described below, the technologicalproperties deteriorate sharply outside the limits indicated.

The cited literature (German Offenlegungsschrift No. 3,510,655) showsthat co-terephthalamides obtained from 50% of p-phenylenediamine plus50% of 3,3'-dimethylbenzidine as well as those obtained from 50% ofp-phenylenediamine and 50% of 3,3'-dimethoxybenzidine are sparinglysoluble in aramide solvents and can not be spun (Comparative Experiments1 and 4).

Aromatic polyaramides with one of the single amine components B, C and Dare generally known.

Thus, it is known to use terephthalic acid radicals andp-phenylenediamine radicals for polyamides, for example from German Pat.No. 2,219,703 cited above. These products are virtually no longersoluble in amide solvents.

The use of benzidines is likewise known. Thus, it is shown in GermanOffenlengungsschrift No. 3,510,655 cited above, Comparative Example 6,that a terephthalamide of 3,3'-dimethylbenzidine is insoluble in amidesolvents and can thus not be spun.

The use of 3,3'-dimethylbenzidine for the preparation of aramides isalso cited in the following printed publications:

German Pat. No. 3,007,063, page 5, line 25,

Vysokomol. Soed. 12 (1970), No. 10, page 2185,

U.S. Pat. No. 3,318,849,

Belgian Pat. No. 569,760,

U.S. Pat. No. 3,671,542 and

U.S. Pat. No. 3,767,756,

P. W. Morgan: "Condensation Polymers", Intersci. Publ. 1965, page 180;Japanese Kokai Tokkyo Koho JP No. 55/71,751 (80/71,751), abstracted inCA 93 (16), 151120k, and Japanese Kokai JP No. 50/154/522 (72/154,522),abstracted in CA 84 (16), 106885s.

The use of 3,3'-dimethoxybenzidine is described, for example, in

DE-A 1,929,713,

J. Polym. Sci. B2, 369 (1964),

U.S. Pat. No. 3,671,542 and

Japanese Kokai Tokkyo Koho JP No. 55/71,751 (80/71,751), abstracted inCA 93 (16), 151120k.

As can be seen from the cited publications, the respective polyamidesare in most cases insoluble in amide solvents, or the filaments uponfrom organic solvents shown only moderate properties.

By contrast, the polyamides of the present invention, which wereprepared using mixtures of the amine components B+C+D in definedproportions, surprisingly are soluble in amide solvents and filamentsspun from them show a high strength and a very high initial modulus.

The preparation of the aromatic polyamides according to the invention iscarried out by solution condensation of aromatic dicarboxylic aciddichlorides with quantities, equivalent thereto, or mixtures of aromaticdiamines in known polyamide solvents, i.e. in aprotic, polar solvents ofthe amide type such as, for example, in N,N-dimethylacetamide,tetramethylurea or especially in N-methyl-2-pyrrolidone. If appropriate,halide salts from the first and second groups of the periodic table canbe added to these solvents in a known manner, in order to increase thesolvent power or to stabilize the polyamide solutions. Preferredadditives are calcium chloride and/or lithium chloride.

This salt addition can be made before the polycondensation or,advantageously, immediately after the addition of the acid chloride.

The polycondensation temperatures are usually between -20° C. and +120°C., preferably between +10° C. and +100° C. Particularly good resultsare obtained at reaction temperatures between +10° C. and +80° C. Thepolycondensation reactions are preferably carried out in such a waythat, after completion of the reaction, 2 to 15 and preferably 5 to 10%by weight of polycondensate are present in the solution. Particularlygood results are obtained in concentrations from 5.0 to 7.5 % by weight.

In the course of the polycondensation, the molecular weight of thepolymer and hence also the viscosity of the reaction batch increase.

A sufficient length of the chain molecule has been reached when theviscosity of the polymer solution obtained in the polycondensationcorresponds to an inherent viscosity of the polymer from about 5.0 to9.0 dl/g.

Inherent viscosity is understood to mean the expression ##EQU1##

In this equation, η_(rel) is the relative viscosity and c is the appliedconcentration in g/100 ml.

For the purposes of the present invention, it was determined onsolutions of in each case 0.5 g of polymer in 100 ml of 98% by weightsulfuric acid at 25° C.

The process, sketched out and known per se, for the preparation ofaromatic polyamides is, as far as it is used for preparing the aromaticpolyamides according to the invention as described above, likewise asubject of the invention. This process according to the inventioncomprises reacting 95 to 100 mol % of acid chlorides of the formula

    Cl--OC--Ar--CO--Cl                                         (A')

and 0 to 5 mol % of aromatic dicarboxylic acid dichlorides (E')containing m-bonds with an equivalent quantity of a diamine mixturecomposed of 95-100 mol % of a mixture of diamines containing 20-30 mol%, preferably 25-30 mol %, of diamines of the formula

    NH.sub.2 --Ar'--NH.sub.2                                   (B')

35-55 mol %, preferably 40-50 mol %, of diamines of the formula ##STR3##and 15-40 mol %, preferably 25-30 mol %, of diamines of the formula##STR4## and of 0 to 5 mol % of aromatic diamines (F') containingm-bonds, in the manner indicated.

Aromatic dicarboxylic acid dichlorides containing m-bonds and aromaticdiamines within the meaning of the present invention are those in whichthe directions of the bonds of the two carboxylic acid chloride groupsand of the two amino groups form an angle between one another whichcorresponds to that of m-bonds. Examples of such dicarboxylic aciddichlorides and diamines, respectively, are isophthalic acid dichloride,m-phenylenediamine, 3,4'-diaminodiphenyl or alkyl- and/oralkoxy-substitution products thereof, or 3,4'- or3',4-diaminobenzanilide.

In this procedure, the resulting polyamides according to the inventionremain dissolved in the solvent.

When the polymer solution has reached the viscosity required for furtherprocessing, the polycondensation can be stopped in the usual manner bythe addition of monofunctional compounds such as, for example, acetylchloride. The hydrogen chloride, which has been formed and is looselybound to the amide solvent, is then neutralized by the addition of basicsubstances. Lithium hydroxide and calcium hydroxide, but especiallycalcium oxide, are suitable for this purpose.

For producing shaped structures from the polyamides according to theinvention, the resulting neutralized solutions of the polyamidesaccording to the invention are filtered, degassed and further process inthe known manner to give filaments, fibers, fiber pulp, films or alsosheets, which are likewise a subject of the invention. This can becarried out, for example, by using a wet-spinning unit, where thepolymer solution is extruded through suitable spinnerets into acoagulation bath, the resulting filaments are pulled through washingbaths and drawn at a higher temperature. Suitable coagulation baths areaqueous solutions of the same amide solvent which was also used forpreparing the polymer. However, aqueous salt solutions such as, forexample, calcium chloride solutions can also be used.

When the polymer solutions are extruded and the shaped structures suchas filaments or films are taken off out of the coagulation bath, onlyrelatively slight wet drawing of these structures takes place. Thestructures taken off out of the coagulation baths must therefore besubjected to further drawing after the usual washing and drying, inorder to confer on them the desired mechanical properties, such as ahigh modulus of the elasticity and a high tensile strength.

In the production of the filaments and fibers as well as films andsheets according to the invention, the total drawing is thus composed ofa slight wet drawing and subsequent more extensive drawing. As a rule,the latter is carried out in the usual manner at an elevated temperatureon drawing units, in which single-stage or multi-stage drawing takesplace between two godet rolls running at different circumferentialspeeds.

In order to heat the filaments to be required drawing temperature,contact drawing can be carried out, in which the filaments are pulledover hot plates ("pressing irons") fitted in the drawing region of thedrawing unit, which have surface temperatures from 280° C. to 480° C.,preferably 340° C. to 450° C. The filaments are thus drawn in a ratio of1:4.8 up to about 1:15, preferably 1:5 to 1:13.

A likewise suitable variant of the spinning process is the so-called"dry-spinneret/wet-spinning process", as is described, for example, inUS-A-3,414,645. In the latter, spinning takes place from the topdownwards and, after leaving the spinneret, the spun filaments firstpass through a gaseous medium, preferably air, and enter an aqueouscoagulation bath. The further treatment of the filaments thus producedtakes place a described above. The shaped articles produced from the rawmaterials according to the invention, such as, for example, fibers,filaments, fiber pulp or films and sheets, are used, for example, asreinforcing materials for plastics or as industrial materials forfiltration and insulation. For insulation purposes, it is also possibleto apply a polymer solution as a film to the object which is to beinsulated and then to remove the solvent and any solubilizers which maybe present.

The examples which follow are intended to serve further clarification ofthe invention. The proportions of dicarboxylic acid components anddiamine components were calculated as 100 mol % in each case.

EXAMPLE 1

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 50 mol %of 3,3'-dimethylbenzidine, 25 mol % of p-phenylenediamine and 25 mol %of 3,3'-dimethoxybenzidine, 5 percent polymer solution.

233.5 g (1.1 mol) of 3,3'-dimethylbenzidine, 59.5 g (0.55 mol) ofp-phenylenediamine, 134.2 g (0.55 mol) of 3,3'-dimethoxybenzidine and66.5 g of lithium chloride are dissolved under nitrogen in 13,233 g ofN-methylpyrrolidone and reacted between 30° C. and 55° C. with 446.6 g(2.2 mol) of powdered terephthaloyl chloride. After a reaction time of50 minutes, the polycondensation is stopped by addition of solution of3.4 g of acetyl chloride in about 100 g of N-methylpyrrolidone. The veryviscous batch was stirred for a further 15 minutes at about 60° C. andneutralized with 132.4 g of calcium oxide (96%) in the form of a 65%suspension in N-methylpyrrolidone.

The solution contains 5% of copolyamide, 1.7% of calcium chloride and0.5% of lithium chloride. The dissolved copolyamide has an inherentviscosity of 6.26.

The solution is filtered, degassed and spun by the so-calleddry-spinneret/wet-spinning process. For this purpose, it is spun out, ata temperature of 90° C. through a spinneret fitted at a distance of 30mm vertically above a coagulation bath and having 100 orifices of 0.15mm diameter each into a coagulation bath composed of an aqueous 35%solution of N-methylpyrrolidone in water of 80° C. at a speed of 16m/min. The spun filaments obtained are taken off through two waterbaths, a multi-stage washing machine, over three drying godets at 120°C., 160° C. and 240° C. and finally over a four part hotplate(contactheater) at 360° C., 370° C., 380° C. and 400° C. at a speed of 85.7m/min.

Here and in the following examples, the multifilament yarn is providedwith a protective twist according to αm=30 (DIN 53 832, part 1) and thentested. In this example, the filament denier is 1.77 dtex (DIN 53 830)and the ultimate tenacity together with an ultimate tensile strengthelongation of 2.1% is 185 cN/tex (DIN 53 834, part 1). The modulus is 94N/tex. The modulus is calculated from the slope of thetenacity/elongation diagram between 0.3 and 0.5% elongation.

If, in place of p-phenylenediamine, the equivalent quantity of2-methyl-1,4-diaminobenzene is used and the procedure following in otherrespects is as described above, a fiber material is likewise obtainedwhich, at a reduced but still adequate tenacity, has a very good initialmodulus of 83 N/tex.

EXAMPLE 2

Aromatic copolyamide from 100 mo. % of terephthaloyl chloride, 50 mol %of 3,3'-dimethylbenzidine, 25 mol % of p-phenylenediamine and 25 mol %of 3,3'-dimethoxybenzidine, 6 percent of polymer solution.

254.8 g (1.2 mol) of 3,3'-dimethylbenzidine, 64.9 g (0.6 mol) ofp-phenylenediamine, 146.6 g (0.6 mol) of 3,3-dimethoxybenzidine and 90.7g of anhydrous calcium chloride are dissolved under nitrogen in 11,825 gof n-methylpyrrolidone.

In the course of 60 minutes, 490.2 g of powdered terephthaloyl chlorideare added at temperatures between 29.6 and 57.3° C. After 60 minutes,the polycondensation is stopped by addition of 3.8 g of acetylchloride--diluted with about 100 g of n-methylpyrrolidone. Stirring iscontinued for 10 minutes at about 60° C. and the mixture is neutralizedwith 223 g of a 65% suspension of 96% calcium oxide inN-methylpyrrolidone.

The solution contains 6% of copolyamide and 2.7% of calcium chloride.The copolyamide has an inherent viscosity of 7.5. The solution isfiltered, degassed and spun by a dry-spinneret/wet-spinning process (cf.Example 1).

Temperature of the spinning solution: 120° C.

Spinneret/coagulation bath distance: 20 mm

Spinneret: 100 orifices of 0.15 mm diameter each

Coagulation bath: 35% N-methylpyrrolidone/water at 80° C.

Take-off speed: 60 m/minute

Drying godets: 120°, 160°, 240° C.

Hotplate temperature: 450° C.

Take-off speed: 120 m/minute

The filament denier is 1.81 dtex, the tenacity is 156 cN/tex, theelongation is 1.9% and the initial modulus is 89 l N/tex.

EXAMPLE 3

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 50 mol %of 3,3'-dimethylbenzidine, 25 mol % of p-phenylenediamine and 25 mol %of 3,3'-dimethoxybenzidine, 6.5 percent polymer solution.

A solution of 276.0 g (1.3 mol) of 3,3'-dimethylbenzidine, 70.3 g (0.65mol) of p-phenylenediamine, 158.8 g (0.65 mol) of3,3'-dimethoxybenzidine and 120 g of anhydrous calcium chloride is11,709 g of N-methylpyrrolidone is polycondensed with 527.85 g (2.6 mol)of powdered terephthaloyl chloride as in Examples 1 and 2.

After stopping with 4.1 g of acetyl chloride and neutralizing with 241 gof calcium oxide suspension in N-methylpyrrolidone (65% CaO), this givea very viscous polymer solution.

Copolymer content: 6.5%

Calcium chloride content: 3.15 %

Inherent viscosity of the copolyamide: 6.86 dl/g.

The solution is filtered and degassed. The dry-spinneret/wet-spinningprocess is carried out under the following conditions:

Temperature of the spinning solution: 110° C.

Spinneret/coagulation bath distance: 40 mm

Spinneret: 100 orifices of 0.15 mm diameter each

Coagulation bath: 50% N-methylpyrrolidone/water at 6020 C.

Take-off speed: 16 m/minute

Drying godets: 120°, 160°, 240° C.

Hotplate temperature: 400°-420° C.

Take-off speed: 152.8 m/minute.

The filament denier is 2.69 dtex, the tenacity is 153 cN/tex, theelongation is 1.9% and the initial modulus is 88 N/tex.

EXAMPLE 4

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 40 mol %of 3,3'-dimethylbenzidine, 30 mol % of p-phenylenediamine and 30 mol %of 3,3'-dimethoxybenzidine.

186.8 g (0.88 mol) of 3,3'-dimethylbenzidine, 71.3 g (0.66 mol) ofp-phenylenediamine, 161.2 g (0.66 mol) of 3,3'-dimethoxybenzidine and70.5 g of anhydrous calcium chloride are dissolved in 13,078 g ofN-methylpyrrolidone and the solution is reacted between 30.1° C. and55.3° C. with 446.6 g (2.2 mol) of terephthaloyl chloride in the courseof 38 minutes.

The reaction is stopped with 3.5 g of acetyl chloride and the mixture isneutralized with 204 g of calcium oxide suspension (65% of CaO).

The solution contains 5% of copolyamide and 2.2% of calcium chloride.The inherent viscosity of the dissolved polymer is 8.29. The filteredand degassed solution is subjected to a dry-spinneret/wet-spinningprocess under the following conditions:

Temperature of the spinning solution: 120° C.

Spinneret/coagulation bath distance: 40 mm

Spinneret: 100 orifices of 0.15 mm diameter each

Coagulation bath: 35% N-methylpyrrolidone/water at 80° C.

Take-off speed: 14 m/minute

Drying godets: 120°, 160°, 240° C.

Hotplate temperature: 400°-420° C.

Take-off speed: 180.6 m/minute.

The filament denier is 1.6 dtex, the tenacity is 176 cN/tex, theelongation is 2.1% and the initial modulus is 91 N/tex.

EXAMPLE 5

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 45 mol %of 3,3'-dimethylbenzidine, 25 mol % of p-phenylenediamine and 30 mol %of 3,3'-dimethoxybenzidine.

A solution of 248.4 g (1.17 mol) of 3,3'-dimethylbenzidine, 70.3 g (0.65mol) of p-phenylenediamine and 190.5 g (0.78 mol) of3,3'-dimethoxybenzidine in 12,888 g of N-methylpyrrolidone s reactedwith 526.3 g of powdered terephthaloyl chloride. The polycondensationtakes lace between 30.3° and 54.2° C. in the course of 32 minutes. Fiveminutes after the addition of acid chloride, 84.7 g of anhydrous calciumchloride are added.

The polycondensation is stopped with 4.1 g of acetyl chloride, thereaction is allowed to continue for 10 minutes at about 55° C. and themixture is neutralized with 241 g of calcium oxide suspension (65% inN-methylpyrrolidone).

The solution contains 6% of copolyamide and 2.65% of calcium chloride.The inherent viscosity of the dissolved polymer is 7.63.

The filtered and degassed solution is spun by a wet-spinning process.For this purpose, it is spun out from a spinneret having 100 orifices of0.15 mm diameter each into a horizontally arranged coagulation bath,composed of a warm solution of 35% of N-methylpyrrolidone in water at60° C., at a speed of 16 m/minute. The filament runs through washingbaths, drying godets (120°, 160° and 240° C.) and finally over ahotplate at temperatures of 380°-410° C. and is taken off at 77.7m/minute.

The filament denier is 1.99 dtex, the tenacity is 122 cN/tex, theelongation is 1.5% and the initial modulus is 85 N/tex.

EXAMPLE 6

Aromatic copolyamide from 85 mol % of terephthaloyl chloride, 15 mol %of chloroterephthaloyl chloride, 25 mol % of p-phenylenediamine, 60 mol% of 3,3'-dimethylbenzidine and 15 mol % of 3,3'-dimethoxybenzidine.

101.9 g (0.48 mol) of 3,3'-dimethylbenzidine,

21.6 g (0.2 mol) of p-phenylenediamine and 29.3 g (0.12 mol) of3,3'-dimethoxybenzidine are dissolved in 3,997 g of N-methylpyrrolidoneand reacted at temperatures between 15° and 68° C. in the course of 25minutes with a mixture of 138.05 g of terephthaloyl chloride and 28.5 gof chloroterephthaloyl chloride. After 1 hour further stirring time, themixture is neutralized with 74 g of a calcium oxide suspension (65% ofcalcium oxide in N-methylpyrrolidone).

The solution contains 6% of copolyamide and 2.0% of calcium chloride.The inherent viscosity of the copolyamide is 5.84.

The filtered and degassed solution is wet-spun:

Temperature of the spinning solution: 100° C.

Spinneret: 100 orifices of 0.15 mm diameter each

Coagulation bath: 35% N-methylpyrrolidone/water at 80° C.

Take-off speed: 16 m/minute

Drying godets: 120°, 160°, 240° C.

Hotplate temperature: 340°-380° C.

Take-off speed: 69.5 m/minute.

The filament denier is 1.81 dtex, the tenacity is 131 cN/tex, theelongation is 1.7% and the initial modulus is 84 N/tex.

EXAMPLE 7

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 25 mol %of p-phenylenediamine, 50 mol % of 3,3'-dimethylbenzidine, 15 mol % ofdimethoxybenzidine and 10 mol % of 3,4'-diaminobenzanilide.

A solution of 17.3 g (0.16 mol) of p-phenylenediamine, 67.9 g (0.32 mol)of 3,3'-dimethylbenzidine, 23.45 g (0.096 mol) of3,3'-dimethoxybenzidine, 14.5 g (0.064 mol) of 3,3'-diaminobenzanilideand 20.6 g of calcium chloride in 3,822 g of N-methylpyrrolidone isreacted in the course of 65 minutes at temperatures between 13.2° and63° C. with 130.4 g of powdered terephthaloyl chloride.

The mixture is neutralized with 59.2 g of a 65% CaO suspension inN-methylpyrrolidone.

The solution contains 5% of copolyamide and 2.2% of calcium chloride.The inherent viscosity of the copolyamide is 5.46.

The filtered and degassed solution is wet-spun:

Temperature of the spinning solution: 100° C.

Spinneret: 100 orifices of 0.15 mm diameter each

Coagulation bath: 35% N-methylpyrrolidone/water at 60° C.

Take-off speed: 16 m/minute

Drying godets: 120°, 160°, 240° C.

Hotplate temperature: 360°-380° C.

Take-off speed: 126.3 m/minute.

The filament denier is 1.97 dtex, the tenacity if 162 cN/tex, theelongation is 2.3% and the initial modulus is 79 N/tex.

COMPARATIVE EXPERIMENT 1

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 25 mol %of 3,3'-dimethylbenzidine, 25 mol % p-phenylenediamine and 50 mol % of3,3'-dimethoxybenzidine.

61.0 g (0.25 mol) of 3,3'-dimethoxybenzidine, 13.4 g (0.125 mol) ofp-phenylenediamine, 26.5 g (0.125 mol) of 3,3'-dimethylbenzidine and16.6 g of anhydrous calcium chloride are dissolved in 3,912 g ofN-methylpyrrolidone. In the course of 50 minutes, 101.5 g of powderedterephthaloyl chloride are added between 15.1° and 61.3° C. The solutionis neutralized with 30.7 g of calcium oxide (96%).

The solution contains 4% of copolyamide and 1.8% of calcium chloride.The inherent viscosity of the dissolved polymer is 7.43.

The filtered and degassed solution is spun in a wet-spinning processunder the following conditions:

Temperature of the spinning solution: 90° C.

Spinneret: 50 orifices of 0.15 mm diameter each

Coagulation bath: 35% N-methylpyrrolidone/water at 60° C.

Take-off speed: 15.9 m/minute

Drying godets: 160° C, 180° C.

Hotplate temperature: 300°-340° C.

Take-off speed: 60.5 m/minute.

The filament denier is 2.72 dtex, the tenacity is 108 cN/tex, theelongation is 2.1% and the initial modulus is 69 N/tex.

COMPARATIVE EXPERIMENT 2

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 20 mol %of p-phenylenediamine, 20 mol % of 3,3'-dimethylbenzidine and 60 mol %of 3,3'-dimethoxybenzidine.

7.8 g (0.072 mol) of p-phenylenediamine,

15.3 g (0.72 mol) of 3,3'-dimethylbenzidine, 52.65 g (0.216 mol) of3,3'-dimethoxybenzidine and 24.5 g of lithium chloride are dissolved in2,264 g of N-methylpyrrolidone and reacted at 10° to 75° C. in thecourse of 50 minutes with 74.68 g of powdered terephthaloyl chloride.The mixture is neutralized with 22.1 g of calcium oxide (96%).

The solution contains 5% of copolyamide, 1.6% of calcium chloride and1.0% of lithium chloride. The inherent viscosity of the copolyamide is5.30.

The filtered and degassed solution is subjected to a wet-spinningprocess under the following conditions:

Temperature of the spinning solution: 80°C.

Spinneret: 50 orifices of 0.10 mm diameter each

Coagulation bath: 35% N-methylpyrrolidone/water at 80° C.

Take-off speed: 16 m/minute

Drying godets: 160° C, 180° C.

Hotplate temperature: 330°-370° C.

Take-off Speed: 91.7 m/minute.

The filament denier is 1.86 dtex, the tenacity is 85 cN/tex, theelongation is 1.6% and the initial modulus is 65 N/tex.

COMPARATIVE EXPERIMENT 3

Aromatic copolyamide from 100 mol % of terephthaloyl chloride, 15 mol %of p-phenylenediamine, 25 mol % of 3,3'-dimethylbenzidine and 60 mol %of 3,3'-dimethoxybenzidine.

9.7 g (0.09 mol) of p-phenylenediamine, 31.8 g (0.15 mol) of3,3'-dimethylbenzidine, 87.8 g (0.36 mol) of 3,3'-dimethylbenzidine and20.4 g of calcium chloride are dissolved in 3,854 g ofN-methylpyrrolidone.

The solution is reacted in the course of 35 minutes between 13.4° and57° C. with 121.8 g of terephthaloyl chloride. The mixture isneutralized with 36.8 g of calcium oxide (96%).

The solution contains 5% of copolymer and 2.1% of calcium chloride. Theinherent viscosity of the copolyamide is 6.98.

The filtered and degassed solution is wet-spun under the followingconditions:

Temperature of the spinning solution: 90° C.

Spinneret: 50 orifices of 0.10 mm diameter each

Coagulation bath: 35% N-methylpyrrolidone/water at 60° C.

Take-off speed: 16 m/minute

Drying godets: 160°, 180° C.

Hotplate temperature: 320°-360° C.

Take-off speed: 55.4 m/minute.

The filament denier is 2.9 dtex, the tenacity is 87 cn/tex, theelongation is 1.8% and the modulus is 63 N/tex.

We claim:
 1. An aromatic copolyamide, soluble in organic polyamidesolvents, which comprises at least 95 mol % of recurrent structuralunits of the formulae ##STR5## and up to 5 mol % of structural units Eor F or combinations thereof which contain m-bonds and are derived fromaromatic dicarboxylic acids (E') or from aromatic diamines (F') orcombinations thereof, the totals of the mol fractions of the structuralunits A+E and of the mol fractions of the structural units B+C+D+F beingsubstantially the same,--Ar-- and --Ar'-- being divalent aromaticradicals other than biphenylene, the valency bonds of such are in thepara- position or in a comparable coaxial or parallel position and whichare optionally substituted by one or two inert radicals. --R and --R'being different from one another and being lower alkyl radicals or loweralkoxy radicals, and the fractions of the diamine components B, C and Drelative to the total quantity of these diamine components being insidethe following limits:structural unit B: 20-30 mol % structural unit C:35-55 mol %, structural unit D: 15-40 mol %.
 2. A copolyamide as claimedin claim 1, wherein--Ar-- is 1,4-phenylene, 1,4-, 1,5- or2,6-naphthylene and --Ar'-- is 1,4-phenylene or 1,4-, 1,5- or2,6-naphthylene.
 3. A copolyamide as claimed in claim 1, wherein --Ar--and --Ar'-- are 1,4-phenylene radicals which are unsubstituted orsubstituted by a lower alkyl radical or by a halogen atom.
 4. Acopolyamide as claimed in claim 1, wherein --Ar-- and --Ar'-- are1,4-phenylene radicals which are unsubstituted or substituted by amethyl group or a chlorine atom.
 5. A copolyamide as claimed in claim 1,wherein --Ar-- and --Ar'-- are unsubstituted 1,4-phenylene radicals. 6.A copolyamide as claimed in claim 1, wherein--R is a lower alkyl radicaland --4' is a lower alkoxy radical.
 7. A copolyamide as claimed in claim1, wherein --R is methyl and --R' is methoxy.
 8. A copolyamide asclaimed in claim 1, wherein the structural unit containing m-bonds isthe divalent radical of 3,4'- or 3',4-diaminobenzanilide.
 9. Acopolyamide as claimed in claim 1, wherein the fractions of the diaminecomponents B, C and D relative to the total quantity of diaminecomponents are inside the following limits:diamine B: 25-30 mol %diamine C: 40-50 mol % diamine D: 25-30 mol %.
 10. A process forpreparing an aromatic copolyamide of claim 1, by polycondensation of adicarboxylic acid chloride with aromatic diamines in a known polyamidesolvent, optionally in the presence of an alkali metal halide oralkaline earth metal halide, at an elevated temperature, which comprisesreacting 95 to 100 mol % of acid chlorides of the formula

    C13 OC--Ar--CO--Cl                                         (A')

and 0 to 5 mol % of aromatic dicarboxylic acid dichlorides (E')containing m-bonds with an equivalent quantity of a diamine mixturecomposed of 95-100 mol % of a mixture of diamines containing 20-30 mol %of diamines in the formula

    NH.sub.2 --Ar'--NH.sub.2                                   (B')

35-55 mol % of diamines of the formula ##STR6## 1- 40mol % of diaminesof the formula ##STR7## and of 0 to 5 mol % of diamines (F') containingm-bonds.
 11. The process as claimed in claim 10, wherein a mixture ofdiamines is reacted which has the following compositions:25-30 mol % ofB', 40-50 mol % of C', 2- 30mol % of D'.
 12. Shaped structure of thecopolyamide of claim 1.